---
name: "Algorithm::CheckDigits::MBase_001"
section: "3pm"
platform: "linux"
package: "libalgorithm-checkdigits-perl"
version: "1.3.6-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Algorithm::CheckDigits::MBase_001"
---

# Algorithm::CheckDigits::MBase\_001(3pm)

compute check digits for UPC (US)

## NAME

CheckDigits::MBase\_001 - compute check digits for UPC (US)

## SYNOPSIS

```
  use Algorithm::CheckDigits;
  $rv = CheckDigits('upc');
  if ($rv->is_valid('012345678905')) {
        # do something
  }
  $cn = $rv->complete('01234567890');
  # $cn = '012345678905'
  $cd = $rv->checkdigit('012345678905');
  # $cd = '5'
  $bn = $rv->basenumber('012345678905');
  # $bn = '01234567890'
```

## DESCRIPTION

### ALGORITHM

- 1\.

  Add all digits in odd-numbered positions.

- 2\.

  Multiply the sum from step 1 with 3.

- 3\.

  Add all digits in even-numbered positions.

- 4\.

  Add the product from step 2 and the sum from step 3.

- 5\.

  If the sum from step 4 is 0 modulo 10, the check digit is 0. Else the check digit is 10 minus the sum from step 4 taken modulo 10.

### METHODS

- is\_valid($number)

  Returns true only if `$number` consists solely of numbers and the last digit is a valid check digit according to the algorithm given above.

  Returns false otherwise,

- complete($number)

  The check digit for `$number` is computed and concatenated to the end of `$number`.

  Returns the complete number with check digit or '' if `$number` does not consist solely of digits and spaces.

- basenumber($number)

  Returns the basenumber of `$number` if `$number` has a valid check digit.

  Return '' otherwise.

- checkdigit($number)

  Returns the checkdigit of `$number` if `$number` has a valid check digit.

  Return '' otherwise.

### EXPORT

None by default.

## AUTHOR

Mathias Weidner, `"<mamawe@cpan.org>"`

## THANKS

Aaron W. West pointed me to a fault in the computing of the check digit.

## SEE ALSO

perl, CheckDigits, *www.pruefziffernberechnung.de*, *www.export911.com/e911/coding/upcChar.htm*, *www.adams1.com/pub/russadam/upccode.html*, *http://www.upcdatabase.com*.